1. Field of the Invention
This invention relates to a demonstration, test and training system, in particular, to a satellite simulator.
2. Description of Related Art
A satellite simulator in accordance with the inventive arrangements provides advantages over all current demonstration, test and training systems now used. The system provides a novel and nonobvious satellite simulator which is useful as an aid in the test and development of spacecraft command and telemetry software applications and systems for ground stations. Current software applications are available which consist of tools and software components useful in the creation of spacecraft command and telemetry applications for ground stations. For example, Software Technology, Inc. of Melbourne, Fla. has developed and offers for commercial sale a commercial off-the-shelf [COTS] product known as Open Systems COMET, or "OS/COMET.RTM.".
OS/COMET consists of tools and software components useful in the creation of spacecraft command and telemetry applications for ground stations. Because every satellite ground station application is unique, applications such as OS/COMET are designed with an architecture that accommodates tailoring the basic core system to meet mission-specific requirements. For example these systems may be modified or customized to provide for various satellite orbit types, satellite mission profiles, constellation configurations, communications protocols, and message formats, of a wide variety of systems. The core functionality provided by satellite ground station applications, such as OS/COMET or large-scale simulation networks such as the United States Department of Defense's multi-service simulation systems, is normally supplemented by additional COTS products and custom application modules, typically tied to the core system modules through standard network bus interfaces.
Application engineers building systems based on either OS/COMET type standardized software components or other custom developed systems applications for ground stations often need a test bed to evaluate their ground system development applications. Such test beds arise in several different forms but generally are designed to appear to the ground station software under development as a functioning satellite having the basic communications characteristics anticipated for the fully implemented hardware. In this regard, such test bed systems can be viewed as satellite simulators in that they simulate the outward functionality of an actual satellite for a particular system. Typically, such satellite simulators include software modules to generate appropriate communications and telemetry streams and to receive commands in the same manner as the fully implemented satellite would for the particular satellite or group of satellites.
There are several problems with the currently existing approaches to developing satellite simulators. One problem is that conventional satellite simulator systems have traditionally been custom designed and developed for each ground station application and therefore tend to be both costly and prone to their own development issues. Further, while major development programs may invest considerable resources in high-fidelity satellite simulators, application software developers may not always need the full functionality of such products. Also, high fidelity satellite simulators may have development cycles that leave application developers without suitable test harnesses at critical points early in the application software development cycle. These issues suggest a phased implementation approach to the satellite simulator test bed for each particular application. However, the phased approach creates further development issues. In particular, at the early stages of the ground station development cycle, only rudimentary testing may be required such that the test bed may be constructed to operate on a single host computer platform. However, as the ground station development cycle continues, so does the need for a simulator offering a higher degree of fidelity. This normally requires additional development effort, and sometimes entirely new software and hardware to implement the higher fidelity simulator. For example, the host computer on which the more basic simulator was installed may not offer suitable processing power to implement a higher fidelity simulator. Consequently a more powerful host may be required over time. In this regard, it is often the case with very high fidelity simulators that the processing power necessary cannot practically be provided on a single host computer, unless expensive mainframe computers are used.
Finally, even the use of a standardized ground station system such as OS/COMET requires a comprehensive user training program. In this regard, high-fidelity satellite simulators often need be designed with the fidelity and complexity needed for full mission rehearsals and mission time fault isolation and resolution and so on. Such complexity may make adaptation to more basic training programs difficult. Accordingly, there exists a need for a satellite simulator that is easy to manage and is maintainable by its users, so that a working system can be used with confidence when presenting a training exercise to a class, or in various test scenarios.